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How to validate an email address using a regular expression?
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The fully RFC 822 compliant regex is inefficient and obscure because of its length. Fortunately, RFC 822 was superseded twice and the current specification for email addresses is RFC 5322. RFC 5322 leads to a regex that can be understood if studied for a fe...
Why does sudo change the PATH?
This is the PATH variable without sudo:
17 Answers
17
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Defining static const integer members in class definition
My understanding is that C++ allows static const members to be defined inside a class so long as it's an integer type.
7 An...
Convert a JSON string to object in Java ME?
Is there a way in Java/J2ME to convert a string, such as:
14 Answers
14
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Retrieving Android API version programmatically
Is there any way to get the API version that the phone is currently running?
11 Answers
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SQL JOIN vs IN performance?
...ifferent results.
SELECT a.*
FROM a
JOIN b
ON a.col = b.col
is not the same as
SELECT a.*
FROM a
WHERE col IN
(
SELECT col
FROM b
)
, unless b.col is unique.
However, this is the synonym for the first query:
SELECT a.*
FROM a
JOIN ...
Is this a “good enough” random algorithm; why isn't it used if it's faster?
I made a class called QuickRandom , and its job is to produce random numbers quickly. It's really simple: just take the old value, multiply by a double , and take the decimal part.
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Move branch pointer to different commit without checkout
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You can do it for arbitrary refs. This is how to move a branch pointer:
git update-ref -m "reset: Reset <branch> to <new commit>" refs/heads/<branch> <commit>
where -m adds a message to the reflog for the branch.
The general form is
git...
Optional Methods in Java Interface
...nswers here.
The Java language requires that every method in an interface is implemented by every implementation of that interface. Period. There are no exceptions to this rule. To say "Collections are an exception" suggests a very fuzzy understanding of what's really going on here.
It's important...
What are the benefits of using C# vs F# or F# vs C#? [closed]
...rmulate many problems much easier, closer to their definition and more concise in a functional programming language like F# and your code is less error-prone (immutability, more powerful type system, intuitive recurive algorithms). You can code what you mean instead of what the computer wants you to...